The present invention relates to an intraocular lens which may be implanted in the anterior or posterior chamber of the eye after removal of the natural lens of an eye as a result of a cataract condition.
Intraocular lenses have been successfully used to correct impaired vision after cataract surgery. A persistent problem has been the proper fitting of intraocular lenses, thus obviating the necessity of reentry into the eye and replacement of the lens. Also, dislocation of the intraocular lens after placement has caused problems in destruction of endothelial cells, infliction of pain, resulting in reentry into the eye to relocate the errant lens.
Though there is general agreement that posterior chamber placement of intraocular lenses produces an optically superior result, anterior chamber lens is a fairly common procedure. It is believed that placement of an intraocular lens in the anterior chamber of the eye may be accomplished by a less demanding surgical effort. Also, the optical results from an intraocular lens placed in the anterior chamber has been found to be satisfactory. However, there is a distinct danger of destruction of the endothelium layer of the cornea as a result of touching of the same. This touching may occur during the surgical insertion of the intraocular lens or if the intraocular lens in the anterior chamber dislocates or moves forward with changes in the shape of the eye. It has recently been found that it is best for an intraocular lens to not touch the iris portion of the eye in the vicinity of the pupil. For example, U.S. Pat. No. 3,994,027 to Jensen, et al, described a vaulted intraocular lens. Vaulting and adjustability of the fixation mechanism of an intraocular lens has also been found to be useful in the posterior chamber of the eye to avoid touching the iris and to insure that dislocation of the intraocular lens does not occur when the lens is being supported by the ciliary sulcus.
Various designs for flexible or adjustable intraocular lens fixation mechanisms have been proposed. Reference is made to U.S. Pat. No. 4,134,161 to Bayers which shows an intraocular lens mechanism which includes an adjustable leg. The leg may be adjusted before hand or continually adjusted with an elastic spring mechanism. Although this design recognizes the problem associated with the changing dimension of an eye during and after surgery, its use is impractical. The intraocular lens described in U.S. Pat. No. 4,159,546 to Shearing reveals an intraocular lens having springy open looped legs. Although adjustable to a certain extent, the intraocular lens shown therein would dislocate or thrust forward in the anterior chamber causing the problems heretofore described. The same would be true of the lens design shown in U.S. Pat. No. 4,257,130 to Bayers which describes a ribbon loop design. Finally, U.S. Pat. No. 4,296,501 to Kellman describes a hinged leg which determines the overall length of the lens prior to insertion within the eye. Although solving the problem of maintaining a large inventory of lenses, the Kellman lens fails to continually adjust its overall length without movement along the optical axis toward the endothelium layer or the iris in the anterior chamber or toward the iris or vitreous humor in the posterior chamber of the eye (intra capsular surgical procedure).
An intraocular lens which may be placed either in the anterior or posterior chamber of the eye that is adjustable in its overall dimension without thrusting generally at right angles to the deformation force applied would be a very useful advance in the art of manufacture of intraocular lenses and treatment of eye diseases.